cp: read sparse files more efficiently with non regular destination

* src.copy.c (copy_reg): Use fiemap to read sparse files, even
if the output is not to a regular file.
* NEWS: Mention the improvement.

1 files changed, 3 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index e7aef7725..52332bd11 100644
--- a/NEWS
+++ b/NEWS
@@ -36,6 +36,9 @@ GNU coreutils NEWS                                    -*- outline -*-
   cp,install,mv will convert smaller runs of NULs in the input to holes,
   and cp --sparse=always avoids speculative preallocation on XFS for example.
 
+  cp will read sparse files more efficiently when the destination is a
+  non regular file.  For example when copying a disk image to a device node.
+
   mv will try a reflink before falling back to a standard copy, which is
   more efficient when moving files across BTRFS subvolume boundaries.